I have done side jobs out of my garage for years. it is not my intent to make money, just offset some of the costs of equipment , materials, and my playtime in general.
mostly I do some fabrication, machine work, welding, rust repairs...etc
I also do some engine and cylinder head building as I have the stuff to do it.
to answer another question, I do not charge my friends. I get more out of my friends by them returning the favor than I would by exchanging money with them. you start by doing small stuff for them and see what they will do for you. if they return the favor then you do more for them. if they do not return the favor then you just do not have the time....
also when I do work for a friend I expect that they will assist, I am not a shop for you to just drop it off and pick it up. even if you just hang out and hand me tools, I want you to help.
things I have done for friends....engine machine work, engine rebuilding (labor), general machine work, welding (including extensive restoration welding), suspecsion rebuilds, brakes...and the list goes on
you want to make money.., have you seen FLIP THAT HOUSE?
play flip that car...get a car that needs some work that is a bargain. do the work and sell the car for profit. I do not mean to get into a full resto but you can get a car that is not running, get it running and sell it. if you do that you are limited to the liability associated with selling a used car.
buy toolboxes and part them out. I did some of theis a few years back where I would buy a whole toolbox with tools and then sell off the pieces. that is harder to do not with EBAY now but there are still a few deals out there
bob